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giddymachine
Samba Member
Joined: October 21, 2013
Posts: 24
Location: Honolulu
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 Posted: Wed May 08, 2024 5:32 pm Post subject: Cylinder Head exhaust studs done me wrong |
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Hello there folks.
I've got a 78 fi Westfalia and am replacing my rusted out exhaust. I removed the j-pipes as they were pretty mangled and of course the exhaust studs did me dirty. 3 of 8 stayed in and are fine. 3 others came out with the bolts on them but the threads look good in the head.
The other two are the issue. One came out with the threads from the head on it (pic 1) and one came out with what looks like a time-sert still connected to it (pic 2).
the last one is the one I'm really worried about since there does not look to be much meat on the bone. The threads in the head look like they are "kinda" there but damn thats a big hole.
Any suggestions on how to deal with these two? I'm maybe a step or two above a newb and I did replace heads on a 72 Squareback when I was in high school 40 years ago but I'm pretty sure this is something I'm gonna need some help with.
I've searched thru lots of posts on stud misery but haven't seen anything quite like this so figured I'd see if anyone had advice even if its "get new heads".
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1979 Westfalia FI |
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busdaddy
Samba Member
Joined: February 12, 2004
Posts: 51338
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Wed May 08, 2024 5:47 pm Post subject: Re: Cylindar Head exhaust studs done me wrong |
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Ugh..., I'd be looking into thread insert sleeves.
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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50552
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| Posted: Wed May 08, 2024 11:57 pm Post subject: Re: Cylindar Head exhaust studs done me wrong |
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| Yes inserts will work, I have used Type 1 case savers where I needed a really large diameter insert. |
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wrxnofx
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Joined: July 06, 2022
Posts: 253
Location: Richfield, MN
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| Posted: Thu May 09, 2024 10:53 am Post subject: Re: Cylindar Head exhaust studs done me wrong |
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Whatever you do, don't assume that the current hole can be used as a pilot for the drill bit for whatever you drill these out to. Just because the last dipshit might have drilled the hole out doesn't mean they properly lined it up so that the stud is correctly placed for the tight tolerance manifold.
Ask me how I know...
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1977 VW Type 2 Bay Window Westy FI |
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airschooled
Air-Schooled
Joined: April 04, 2012
Posts: 12800
Location: on a bike ride somewhere
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| Posted: Thu May 09, 2024 11:31 am Post subject: Re: Cylindar Head exhaust studs done me wrong |
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| wrxnofx wrote: |
Whatever you do, don't assume that the current hole can be used as a pilot for the drill bit for whatever you drill these out to. Just because the last dipshit might have drilled the hole out doesn't mean they properly lined it up so that the stud is correctly placed for the tight tolerance manifold.
Ask me how I know... |
Were you visited by the same exhaust fairy?
Aluminum is soft and drills easily with a sharp bit. T4 exhaust studs are parallel with each other on each head, but the overalll engine shape has the studs angling away from each other.
//-----engine-----\\
Robbie
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mikewire
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Joined: March 22, 2010
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Location: San Antonio, TX
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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50552
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| Posted: Fri May 10, 2024 8:45 pm Post subject: Re: Cylindar Head exhaust studs done me wrong |
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| wrxnofx wrote: |
Whatever you do, don't assume that the current hole can be used as a pilot for the drill bit for whatever you drill these out to. Just because the last dipshit might have drilled the hole out doesn't mean they properly lined it up so that the stud is correctly placed for the tight tolerance manifold.
Ask me how I know... |
An old manifold flange can be used as a drill guide. Start with a bit that barely fits through the hole in the flange to get things centered well or make a reducer of sorts to fit in the hole in the flange so you can start with a smaller bit. |
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Synergy Solutions
Samba Member
Joined: September 26, 2022
Posts: 114
Location: SoCal
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| Posted: Sun May 12, 2024 4:47 pm Post subject: Re: Cylindar Head exhaust studs done me wrong |
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| airschooled wrote: |
| wrxnofx wrote: |
Whatever you do, don't assume that the current hole can be used as a pilot for the drill bit for whatever you drill these out to. Just because the last dipshit might have drilled the hole out doesn't mean they properly lined it up so that the stud is correctly placed for the tight tolerance manifold.
Ask me how I know... |
Were you visited by the same exhaust fairy?
Aluminum is soft and drills easily with a sharp bit. T4 exhaust studs are parallel with each other on each head, but the overalll engine shape has the studs angling away from each other.
//-----engine-----\\
Robbie |
Not the same fairy 
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giddymachine
Samba Member
Joined: October 21, 2013
Posts: 24
Location: Honolulu
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| Posted: Mon May 13, 2024 12:49 pm Post subject: Re: Cylinder Head exhaust studs done me wrong |
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Thanks for all the help everyone. Decided to get some professional fix this for me. There wasn't much meat on the bone to drill the bad one larger but luckily the threads were still in decent shape so he cased the threads and re-seated it. The other one he installed a helicoil and its solid now too. Got my exhaust installed with no problems.
Not dealing with a mangled pushrod but that is a story for another thread.
Hope to have her back on the road soon.
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1979 Westfalia FI |
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wrxnofx
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Joined: July 06, 2022
Posts: 253
Location: Richfield, MN
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| Posted: Tue May 14, 2024 9:14 am Post subject: Re: Cylindar Head exhaust studs done me wrong |
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| Wildthings wrote: |
| wrxnofx wrote: |
Whatever you do, don't assume that the current hole can be used as a pilot for the drill bit for whatever you drill these out to. Just because the last dipshit might have drilled the hole out doesn't mean they properly lined it up so that the stud is correctly placed for the tight tolerance manifold.
Ask me how I know... |
An old manifold flange can be used as a drill guide. Start with a bit that barely fits through the hole in the flange to get things centered well or make a reducer of sorts to fit in the hole in the flange so you can start with a smaller bit. |
That was my plan, too. I bought an old manifold for this purpose. However, the hole in the head was already drilled larger than the flange hole diameter. So I need to enlarge the hole in the flange to a diameter that might be larger than the flange itself. Basically, to fix it properly I need to insert an M10 time-sert and use a stepped stud (M10 to M8 ), so the hole for that thing is way larger than the meat on the flange. Consequently, I'm not sure what I can use as a drill guide.
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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50552
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| Posted: Tue May 14, 2024 9:37 am Post subject: Re: Cylindar Head exhaust studs done me wrong |
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| wrxnofx wrote: |
| Wildthings wrote: |
| wrxnofx wrote: |
Whatever you do, don't assume that the current hole can be used as a pilot for the drill bit for whatever you drill these out to. Just because the last dipshit might have drilled the hole out doesn't mean they properly lined it up so that the stud is correctly placed for the tight tolerance manifold.
Ask me how I know... |
An old manifold flange can be used as a drill guide. Start with a bit that barely fits through the hole in the flange to get things centered well or make a reducer of sorts to fit in the hole in the flange so you can start with a smaller bit. |
That was my plan, too. I bought an old manifold for this purpose. However, the hole in the head was already drilled larger than the flange hole diameter. So I need to enlarge the hole in the flange to a diameter that might be larger than the flange itself. Basically, to fix it properly I need to insert an M10 time-sert and use a stepped stud (M10 to M , so the hole for that thing is way larger than the meat on the flange. Consequently, I'm not sure what I can use as a drill guide. |
The old flange will still be able to help you center the bit and get the angle right. As mentioned start with a bit that barely fits in the flange. Drill with care doing whatever you can to keep the bit from walking. Once you get a hole that is properly aligned you can then go back and drill it larger in steps and the bits should follow the existing hole as you do the enlargement. |
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